Trailer brake system



F eb; 20, 1940.

R. c. HOYT TRAILER BRAKE SYSTEM F iled ma 22, 1957 2 ShetS-Sheet 1 flip/7207' For a l/a/r i 4 110 rnp y Fbb.20,1940. R.C.HOYT

TRAILER BRAKE SYSTEM Filed Nov. 22, 1937 2 Sheets-Sheet 2 the tractor vehicle motor.

Patented Feb. 20, 1940 UNITED STATES PATENT OFFICE 18 Claims.

This invention relates to a brake system for vehicles and particularly to a brake system of the hydraulic type. While the invention may have various applications, it particularly is designed as a brake system for operating the brakes on a trailer vehicle by motor actuated power means as for example, the intake manifold of It is an object of this invention to provide a simple, eiiicient and easily operated brake system for a trailer vehicle and one which may be operated to apply the brakes on the trailer vehicle when the brakes are applied on the tractor vehicle and in which the brakes may be applied to the trailer vehicle independently of the application of brakes to the tractor vehicle.

It is a further object of the invention to automatically accelerate the motor simultaneously with the operation of the brake system either for application or release of the brakes, through the medium of a secondary carburetor system and thereby prevent the motor from missing or stopping due to the dilution of the combustible mixture in the manifold. This increases the efficiency of the vacuum by which the power unit It is still a further object of the invention to.

control and use without loss of power or efiiciency through levers or other means, a sufncient quantity of brake fluid to actuate any system of hydraulic brakes to the maximum braking eificiency regardless of how much the brake mechanism is out of adjustment.

It is also an object of the invention to provide a novel structure of manifold including an additional valve placed in the passage leading from .the carburetor and a conduit extending from the chamber created between the valves in said passage and leading into the mixing chamber communicating with the manifold together with a conduit extending. from said mixing chamber to the brake actuator whereby air drawn through said last mentioned conduit will pass around the end of said last mentioned conduit in said mixing chamber and be eiiiciently mixed with the mixture issuing from said first mentioned conduit.

It is also an object of the invention to provide a brake system for a trailer vehicle comprising an actuator operated by the application of the atmospheric and reduced pressure thereto through a control device connected to the atmosphere'and to the intake manifold of the motor the invention will be fully set forth in the following description made in. connection with the accompanying drawings in which like reference characters refer to similar parts through the sev= eral views and in which:

Fig. l is a perspective view of the various parts forming the brake system of the present invention;

Fig; 2 is a view in central vertical section through said parts;

Fig; 3 is a horizontal section taken on line 3-3 of Fig. '2; as indicated by the arrows, and

Fig. 4 is a vertical section taken on line fl i of Fig. 2, as indicated by the arrows.

Referring to the drawings, a brake system or mechanism fora trailer vehicle is shown. As stated, a novel structure of manifold is used with this system. The mixing chamber or passage of a carburetor is shown as 5 contained within a carburetor member or casting 6. 6 has a flange at one end connected to a flange on the manifold riser I by cap screws 8 which,

' as shown, pass through one of said flanges and are threaded into the other. The passage 5 continues through member 7 and this is the passage which conveys the gas issuing from the carburetor to the motor. In accordance with the present invention two shutter valves 9 and ill respectively are provided and disposed within said passage-havingtrunnions or bearings provided in the castings 5 and i. Control levers H and H are secured respectively to the trunnions of said valves 9 and i0. Lever 82 extends to both sides of its connection to valve Ill. and has pivotally connected to one end thereof a rod l3 forming the connecting rod to the accelerator mechanism. The other end of lever i2 is pivotally connected to a connecting rod i5, said rod being screw threaded at its other end into a casting 56 forming substantially half of a diaphragm control pot. The other half or part of said control pot is formed'by a casting i1, said casting having flanges secured by the headed and nutted bolts l9. A diaphragm l8 has its edge clamped between said flanges and extends across the chamber in said pot which as shown in Fig. 2 is substantially ellipsoidal in form. Diaphragm l8 has connected thereto substantially at its center a connecting rod 2| passing through a packing member l2 carried by casting I1, said rod being pivotally connected at its other end to the end of lever II. A flexible conduit 22 is coupled or connected to a boss 24 on casting l1 and is connected at its other end by a screw threaded and flanged coupling 28 to the upper Said casting 21 so as to communicate with a port 29 in said end member. It will thus be seen that communication is afforded from opposite ends of cylinder 21 to the said diaphragm pot formed by members [6 and 11 at both sides of diaphragm l8 respectively. A jet-forming opening 32 isshown as extending through the wall of member 6 from a chamber 6a adjacent thereto and a valve 3| is provided threaded into the wall of chamber 6a and having a pointed end cooperating with opening 32 to regulate the amount of gasoline issuing therethrough. Another opening or orifice 34 is provided closely adjacent orifice 32 and a plug 4 33 is threaded into an opening in the wall of chamber 6a in alignment with orifice 34, said latter opening forming a cleanout passage. In the decelerated position of the shutter valves 9 and I8 valve 9 assumes a closed position between the idling jet openings 32 and 34. Valve I8 is thus completely closed. The idling mixture supplied from the carburetor is trapped in the cham-. ber or portion of passage 5 between the valves 9 and 18. A conduit 35 is connected at one end by the threaded and flanged coupling 31 to member 1 so as to communicate with chamber 5 through a port 36 disposed between valves 9 and I0. The other end of conduit 35 is connected by a threaded and flanged coupling 31a to an enlarged portion 40 of manifold casting 1 having therein a chamber 39 opening into passage 5 of member 1 through the Venturi tube portion 4 I. A nozzle 38 is aligned with and communicates with conduit 35 and has its end disposed centrally of the Venturi tube portion 4|. A conduit 42 of considerably larger size than conduit 35 is connected by a threaded and flanged coupling member 44 to one of the enlarged portions 40 so as to communicate with the port 43 leading into the chamber 39. The other end of conduit 42 is connected by a threaded and flanged coupling member 45 to a boss on the side of the cylinder 21 so as to communicate with the port 46 leading into said cylinder. It will be seen that an automatic accelerator medium is provided between the control levers II and I2 operated by the atmospheric pressure and reduced pressure produced in the diaphram control pot through the flexible conduits 22 and 23.

Cylinder 21 has movable therein pistons 41 rigidly connected by a sleeve 48, said pistons having peripheral packing rings 49 thereon engaging the wall of cylinder 21. Hubs 50 project at the remote sides of pistons 41 and form stops adapted to engage end members 21a and 21b to properly position the pistons at certain timesin the operation thereof. These stops also insure that ports 46 and 5| will communicate with the chamber formed between said. pistons at all by the bore 51 of said casting through a port 56.

Cylinder 51 has quite a number of ports, six in number, immediate communicating therewith adapted to cooperate in pairs with a valve core 58 slidable in cylinder 51. Member 58 has reduced portions 58a, 58b and 58c thereon and as shown in Fig. 2, it will be seen that these portions provide separate valve chambers in cylinder 51. A coiled compression spring 59 has one end seated in the end of a bore in casting and its other end bearing against one end of valve core 58. Spring 59 holds valve core 58 in the position shown in Fig. 2 which is the released position, at which time the left hand large portion of said core is in theleft hand end of cylinder 51. Member 55 has ports 68 and 65 at one side leading from cylinder 51 to the atmosphere.

Member 55 has a port 62 leading centrally from cylinder 51 to which is connected by the threaded and flanged coupling 64 a conduit63. This conduit is merely provided for some auxiliary connection or service and is otherwise normally closed by a plug 63a. In the released position of member 58 will be noted that port to the atmosphere is closed while port 65 to the atmos-' phere is open and communication is afforded between this port and a port 66 in member 55. Port 66 is at one side of port 62 and another port 6| is spaced from port 62 at the other side thereof. A conduit 61 has one end connected by the threaded and flanged coupling 68 to member 65 so as to communicate with port 6| and has its other end connected by a threaded and flanged coupling 1| to one side of a control member or valve body casting 10 illustrated as formed integrally with the end casting 21b of cylinder 21. Conduit 61 communicates with a port 69 leading into a cylinder 89 formed by the bore in member, 18. It may be pointed out that cylinder 21 is "secured to the end members 21a and 21b by the cap screws 12. A conduit 11 has one end connected to cylinder end member 21a by a threaded and flanged coupling member 82 so as to communicate with cylinder 21 through a port 80. Conduit 11 is connected at its other end by a threaded and flanged coupling member 19 'to member 10 so as to communicate with cylinder 89 through a port 18. A conduit 13 is connected by a threaded and flanged coupling member 14 to member 55 so as to communicate withport 66 and is connected at its other end by a threaded and flanged coupling member 16 to one end of member 18 so as to communicate with a port or passage 15 in member 10, said port leading into cylinder 89 and as illustrated, substantially opposite port 85 to be later described. A conduit 84 is connected at one end by the threaded and flanged coupling 88 to end member 21b of cylinder 21 so as to communicate with said cylinder through a port 81 and said conduit is connected at its other end by a threaded and flanged coupling 86 to the member 18 so as to communicate with cylinder 89 through port 85.

The valve structure in member 18 is similar to-that in the member 55 in that there is a cylinder with ports cooperating in pairs through the function of a valve member or valve core. In the member 10 the valve core or member is'shown as 90', the same fitting slidably in cylinder 89 and having reduced portions 98a, 98b and 900 respectively. A compression coiled spring 91 has one end engaging the bottom of a reduced bore in the lower end of the cylinder 89 and the same has its other end engaging a cup sealing member 92 disposed against the lower end of member 99. Said member 92 has a peripheral flange directed away from member 90. A compression coiled spring 93 has one end engaging the top of a reduced bore at the upper end of cylinder 39 and said spring has its other end engaging a cup sealing member 94 which engages the top of member 90. Member 94 also has a peripheral flange at one side directed away from member 90. The spring 93 is of greater strength than the spring 9| and normally .holds the member 90 in its lower position which is the released position of the brake mechanism. Member I0 has a port or passage 95 communicating with the lower end of cylinder 89 andextending to the atmosphere. When member 90 is in its lower or released position as shown in Fig. 2, member 90 closes off port 95 from the adjacent or cooperating port 78.

The hub 48 connecting pistons 41 in cylinder. 2? is bored to receive a hollow piston 96 secured in said hub' with a press flt and also held therein by set screws 91. A vent tube 98 is disposed in piston 96 extending adjacent one wall thereof and having one end secured therein and communicating with cylinder 21 through an aperture in one of the hubs 50. The other end of vent tube 20 is adjacent the upper or left hand end of piston 96. The end of piston 96 is closed by a plug 99 threaded into the end of said piston, the same being shown as having a transverse groove I00 therein at its outer side for the application of a'tool'for its removal. A similar plug IOI is threaded into theprojecting cylindrical hub of end member 21a of cylinder 2'! and the same has a transverse groove I02 at its outer side adapted to receive a tool for its removal. The chamber in piston 96 forms a brake fluid reservoir. The right hand or lower end of piston 96 is engaged at its outer side by a sealing cup member I03 which may be made of rubber or leather. Said cup member has a peripheral flange directed away from piston 96 and engaging the wall of the cylinder or bore I99 in the portion .connecting member I0 and end member 2%. Cup member I 03 is held in place by a coiled compression spring I04, one end of which engages member I03 within the flange thereof and the other end of which engages the end of said cylinder in which it is disposed. Spring E04 holds piston 96 in the position shown in Fig. 2 which is the released position of the brake mechanism. A sealing ring I05 is fitted in an annular groove in the periphery of piston 96 adjacent the end thereof which acts to prevent brake fluid from passing from cylinder I09 into cylinder '21. A groove or chamber 96a is formed about piston 96 between cup members I03 and I05 which chamber communicates with the interiorof piston 96.

through the port or passage I06. The lower or right hand end of the piston 96 is closely fitted to the wall of cylinder I09 and the same has a' plurality of small holes I91 extending from groove 96a to the end of the piston and the cup member I03. The passage 08 is provided in member 70 at one side of port I5 and extends to the upper reduced portion of cylinder 89 which contains the spring 93. Said passage I08 is sepa rate from passage 75. A bypass portion or passage II8 extends from cylinder I09 at spaced points to provide a passage for brake fluid from cylinder I09 to the groove 96a. A passage III] extends through member I0 from cylinder I09 to the lower end of member l0 and communicates with a flexible conduit H2, one end of whichis secured to member I0 by a threaded and flanged coupling member II3. The other end of conduit H2 is connected by a threaded and flanged coupling member II 6 to a boss ona tractor-carried coupling casting H5. Member II! has formed therein a chamber II'I forming a fluid pressure chamber and cylinder or fluid chamber 309 is thus in communication with this pressure chamber through conduit. II2. A similar coupling casting I20 is provided which will be mounted on the trailer unit a portion of which is shown by the plate IZI. Casting I20 extending through an opening in plate HI and having a flange connected to said plate by the screws I22. Casting I20 has formed therein a pressure chamber II9 similar to chamber I". A conduit I23 is connected to a boss on member I20 by a threaded and flanged coupling member I25, said conduit communicating through a port I39 with chamber II9. Conduit I23 will beconnected to the brake cylinders of the trailer unit. The coupler casting I20 is bored at one end to provide a cylinder I26'in which a sleeve valve I21 fits and slides. A compression coiled spring I28 is disposed in cylinder I26 having oneend engaging valve I21 and its other end engaging a plug I29 threaded into the end of member I20 and closing cylinder I26. Plug I29 is provided with a transverse groove I30 adapted to receive a tool for removing said plug. A valve member or core I3I has one end fitted in and secured to valve I2! as shown in Fig. 2. A coupler casting II5 which is carried on'the tractor is also bored at one end to-provide a cylinder I32 and valve member I3I has a flange at one end fitted to reciprocate in cylinder I32. A coiled compression spring I33 surrounds valve I3I having one end bearing against the inner side of the flange thereon and its other end engaging member H5 at the end of cylinder I32. Springs I26 and I33'thus act to urge valve member I3I to the right as seen in Fig. 2. Cylinder I32.is closed at one end by a plug I34 threaded therein, which plug is bored coaxially with cylinder 32 to form a bearing for a coupling valve stem I35. Valve stem I35 extends into and is secured to one end of valve I3I. Centrally located in the valve core or valve member I3I is a passage I36 extending axially of said member and having passages at its end which extend radially to the outer side' of member I3I. Passage I36 forms a conduit coupling provision providing brake fluid communication between the pressure chamber H9 in the trailer coupler casting I20 and the pressure chamber III in the tractor coupler casting II5. This provision enables the brake fluid to be transmitted by a bore operated master cylinder to the brake cylinders of the trailer unit through conduit I23. The member I3! is sealed by cup members 33'! disposed at the ends of chambers Ill and H9 respectively, the same having peripheral flanges facing each other and having flanges surrounding and engaging member i3I. A pair of annular grooves are formed in member II3 about the bore receiving member I3I, which grooves have disposed therein sealing rings I38 which will be made of rubber or similar suitable material. At certain times the radial passages from passage I36 align with packing rings I39 and thereby prevent the brake fluid from leaking out outer end of valve stem I36. Lever I and attached parts thus constitutes a lever mechanism enabling an operator to compress springs I33 and I28 during the coupling operation. A locking means (not shown). of any suitable type will be disposed on the trailer unit to hold the conduit coupling means engaged and this will engage the end of lever I45.

A master cylinder casting I46 is shown, thll being of the conventional type of such a cylinder for operating a brake mechanism. Said cylinder has an outlet port I41 with which communicates a brake fluid conduit I48 secured to said cylinder by a threaded and flanged coupling member I49. Conduit I48 will extend to the brake cylinders of the tractor vehicle. Member I 46 is shown as having projecting from one side thereof parts forming a chamber I 66 to which parts is secured a cover I58 for said chamber by means of cap screws I54. Cover I50 has threaded into a boss thereon a filler tube I5I shown as having thereon a knurled closing cap I 52. A vent opening I53 will be provided in the top of cap I52 for chamber I 66 so that atmospheric pressure will be maintained therein. A port I55 also leads from the chamber I58 in member I46 and a conduit I56 communicates with said port, the same being secured at one end to member I46 by a threaded and flanged coupling member I 51. Said conduit is connected at its other end to member III by a threaded and 'flanged coupling member I66 so as to communicate with cylinder 89 through a port I59. Communication is thus provided for a brake fluid to pass from chamber I58 of the master cylinder to the reduced bottom portion of bore or cylinder 89. A piston I6I is disposed in cylinder I58, the same having a pressure sealing cup member I63 at its lower end, said cup having a peripheral flange directed away from said piston. A tapered coiled compression spring I64 has its larger end engaging the bottom of chamber I58 and its upper and smaller. end engaging the central portion of cup I63. Spring I 64 has suflicient strength to normally move piston I6I to its released position when the pedal assembly or operating assembly (not shown) for piston I6I is not in operation. A bypass port I65 connects the brake fluid chamber or reservoir I66 to the cylinder I58 just below I or in front of piston I6I or its cup member I63 when in release or inoperative position. A port I61 provides communication from brake fluid chamber I66 to chamber I68 above sealing member I63 and the lower-end of piston I6I. Piston I6I has another sealing cup member I 62 surrounding the samespaced from and above cap member I63, member I 62 also having a peripheral flange engaging the wall of cylinder I58 and directed toward the end of said piston which engages member I63. Chamber I66 will, as above stated, have a vent passage therein so that chamber I68 between members I62 and I63 will at all times be kept at atmospheric pressure through the port I61. A pluralityof small holes I69 extend from chamber I68 through the flange or end of piston I6I to the inner side of cup member I63. Member I46 is shown as having a flange surrounding the same adjacent its top to receive bolts for attaching said member to a suitable support.

It is pointed out that in the brake system disclosed a fluid brake mechanism of the conventional character applied by a pedal or other mechanism (not shown) is operated in a reciprocating balance with a power actuated fluid ports operated by the vacuum or reduced pressure and. by atmospheric pressure are shown in their reciprocable positions of release. The positions of release is of course.thepositionoocupied by the ports when the brakes are not applied. The vacuum or reduced pressure will extend to all of the conduits communicating with the man ifold by means of which the reduced pressure or vacuum is produced. The atmospheric; pressure will, of course extend to all parts in communication with the atmosphere. fluid for the most part is indicated in the drawing, it will be understood and assumed that all of the brake fluid chambersor-conduits receiving the fluid are full of the braking fluid and that no actuating pressure is being applied to the fluid in the showing in Fig. 2. The elements in said brake fluid chambers are also shownrin release position.

In accordance with synchronized movement of the piston assembly in cylinder 21 the diaphragm I9 is indicated in its extreme position of release which holds the shutter valve 9 in its decelerated position between the idling jet orifices 32 and 34. By this provision gas issuing from jet 32 will constitute the gas portion of the idling mixture which in accordance with the invention is trapped by the additional shutter valve I 9. This valve is connected to the diaphragm control pot casting member I6 by the lever I2 and connecting rod I5. The idling mixture thus trapped is communicated through the conduit 35 to the nozzle 38 which is disposed in proper position centrally of the Venturi tube 4| to provide maximum carburation on the release cycle or in the released position of the brakes.

Assuming that the idling effect of the tractor vehicle is producing a movement through passage 5 the vacuum will communicate with the mixing chamber 39 through the Venturi tube 4| and through port 43, the conduit 42 and port 46 to the chamber between the pistons 41.

This vacuum or reduced pressure is constantly maintained in cylinder 21 between pistons 41 and this is communicated at all times through conduit 52 to the valve chamber at the center of valve core or member 58. With the member 58 in its position at the left hand end or top of cylinder 51, said valve member shuts off the atmosphere through port 68. The vacuum is shut off from port 66 which is in communication with the atmosphere through port 65. It is seen that valve 58 is thus maintained in its release position as shown in Fig. 2. The reduced pressure is communicated through port 6I, conduit 61, port 69 and cylinder 89 between the large or non-reduced portions of valve core or member 98, thence to port I8, conduit 11 and port 88 to cylinder 21 at the left hand end or the upper ends of piston 41 at the left or upper end of cylinder 21. At the same time atmospheric pressure is communicated through port 66, conduit I3, port 15 to cylinder 89 about reduced portion 980 of valve core member 99 and thence through the port 85, conduit 84 and port 81 to cylinder 21 at the right hand side of lower or right hand piston 41. With this condition it is apparent that pistons 41 are maintained at the upper or left hand side of cylinder 21 and'that valve core or member 58 is maintained in the position shown at the left Whereas no ber 98 in the release position as shown in Fig. 2..

Atmospheric pressure which is present in port 95 at all times is thus shut off from port I8 by the lower large or unreduced portion of member 98. The upper large or unreducecl portion of member 98 prevents the vacuum from being communicated to ports I5 or 85. As already described, atmospheric pressure is delivered through these ports and member 98 is thus held in its release position as shown in Fig. 2.

As stated, when the trailer coupling members H5 or I28 are in position the lever I45 will cupy the position shown in Fig.2 and will be locked inthis position. When the operator moves piston I6I, in cylinder I58 by the usual I pedal or other brake applying mechanism, a fluid pressure will be created in cylinder I58 sumcient to operate the actuating pistons in the wheel brake cylinders (not shown) of the tractor vehicle through conduit I48. Because a spring is arranged in retraction capacity across the brake elements approximately 50 pounds of fluid pressure is ordinarily required prior to 50 pounds of fluid pressure being established in the master cylinder.

When the piston I6I is operated as described the fluid pressure created in chamber I58 is transmitted through conduit I56 and port I59 to the lower reduced end of cylinder 89 and applied against the lower end of valve member or core 98. Said member 98 is thus forced upward compressing spring 93 and said member moved upward until the upper large or unreduced portion engages the upper end of the cylinder 89. When member 98 thus moves upward port I is shut off from port 85 and port I8 is cut off from port 69. Reduced pressure is still maintained between the pistons 41 and this reduced pressure or vacuum is now transmitted through port 5 I, conduit 52 the chamber in cylinder 51 about reduced portion 58b of valve 58, through port 6| and conduit 61 to port 69. With member 98 moved upwardly as described, port 69 will be put into communication with-port 85 by the chamber about reduced portion 98b of member 98. Vacuum will thus be transmitted through said port 85 and conduit 84 through port 81 to cylinder 21 at the lower or right hand side of the lower or right hand piston 41. At the same time atmospheric pressure will be transmitted from port or passage 95 to the chamber in cylinder 89 about the reduced portion 98a of member 98 through port I8 and conduit II and through port 88 to cylinder 21 at the upper or left hand side of the upper or left hand piston 41. The vacuum or reduced pressure is thus now applied to the right hand end of cylinder 21 while atmospheric pressure is transmitted to the left hand or upper end thereof and pistons 41 are accordingly caused to move to the right. The application cycle of the upper actuated mechanism is thus accomplished and when pistons 41 move to the right as shown in Fig. 2 piston 96 is moved in cylinder I89. It will be understood that cylinder I89 is filled with brake fluid. Movement of piston 96 creates pressure on the brake fluid and this pressure is transmitted through passage I I8, conduit H2 and through port'I I4 to the pressure chamber III. The pressure is then transmitted through the fluid in the conduit coupling provision formed by passages I36 and thus transmitted to pressure chamber II9. From chamber II9 the pressure is transmitted through port I24 and conduit m to the trailer brake wheel cylinders and the brakes will be applied to the trailer.

When pressure is created in cylinder I89 as described, this is transmitted through passage I88 to the reduced upper end of cylinder 89 above valve member or core 98 and the'pressure thus applied to said member causes the same to move downwardly to a position of lap. In this position communication between the cooperating ports is shutoff and a balance is established between the foot applied brake pressure and the power applied brake pressure. The fluid pressure created through the power actuated mechanism will then not increase or decrease except. by control of the operator.

The release cycle of the mechanism takes place when the pressure is released on piston I6I which has been applied by the pedal or other mechanism. When this occurs the brake fluid pressure in cylinder I58 will simultaneously reduce to atmospheric pressure through port I65 which as stated, is in communication with atmospheric pressure on the brake fluid in reservoir I66. Valve member or core 98 will at once then move to its position of release shown in Fig.

2 by the action of spring 93. When member 98 moves to this position the vacuum and pressure will be applied as already described so that thepistons 41 will be moved to the left or top portion of cylinder 21 to the position shown in'Fig. 2. The ports are thus returned to release position.

On the power actuated release stroke of the piston assembly in cylinder 21, that is when pistons 41 move to the left as shown in Fig.2, the piston rod 96 will also be moved to the left and to its position of release as shown in Fig. 2 and this will take place before the piston assembly in the wheel cylinders of the trailer unit are fully moved to the position of release and thus, before all of. the. fluid is discharged from said cylinders. This condition is compensated for by brake fluid in the reservoir or chamber within piston 96'passing through port I86 into the annular chamber96a and thence through bypass H8. The flange on cup member I83 in the retraction of piston 96 will be disposed contrary to:

its sealing tendency. Brake fluid will also pass through holes I 81 in the end of piston' 96 into" the fluid chamber I89. The chamber I89 can thus flll with brake fluid before the trailer wheel cylinder assembly is fully released, and before all of the brake fluid is discharged from said assembly. Fluid can subsequently pass through bypass H8 back into the piston 96. Atmospheric pres-' sure is in communication with the left hand end portion of the brake fluid reservoir within piston- 98 on its release movement through the vent tube 98.

The brakes can also be applied on the trailer by operation of valve member or core 58. Said member has an actuating flange 5842 at its outer end and this can be actuated by the operator either directly or through any desiredmechanism. When member 58 is thus moved it moves to the right as shown in Fig. 2 and spring 59 is' and port 81 into the right hand end or lower pheric pressure through port 69 will be communicated in chamber 51 about the reduced portion 580 of member 58 to port BI and thence through conduit 6! and port II to the chamber in cylinder 89 about reduced portion 90b and from said chamber through port 18, conduit 71 and port to the upper or left hand end of cylinder 21 at the left hand side of the upper or left hand piston 41. Reduced pressure is thus at the right of pistons 41 and atmospheric pressure at the left so that said pistons will again be moved to the right, thus moving piston 96 creating pressure on the brake fluid in chamber I09. Atmospheric pressure in the left hand end. or upper end of cylinder 21 will also communicate through port 26, the conduit 21 and through the boss 24 to the left hand side of diaphragm I8 in the control pot formed by members I6 and I "I.

Upon pressure being relieved on port 58d of member 58 the released spring 59 will return valve member or core 58 to its position of release shown in Fig. 2 and this will cause all of the ports in member 55 to register as shown. This will again put vacuum or reduced pressure into the left hand or upper end of the cylinder 21 and atmospheric pressure into the right hand end of pistons 41 and piston 96 will be moved back to the release position shown in Fig. 2. The atmospheric pressure and reduced pressure will also be reversed in the control pot formed by members IE and I! and diaphragm I8 will be moved to the position shown in Fig. 2. It will thus be seen that the brakes can be set on the trailer independently of the operation of the brakes on the tractor vehicle.

It will be understood that shutter valve 9 in the passage is shown in the normal idling position with the brakes in the release position. When vacuum is applied to the right hand or 'lower end of the cylinder 21 it is also communicated through conduit 23 to the right handside of the pot formed by members I6 and I1. This moves diaphragm I8 to the right as shown in Fig. 2 thus moving rod I! and swinging lever I I. This moves shutter valve 9 to the dotted. lineposition shown in Fig. 2 and this cuts in jet orifice 34 thus supplying more fuel to the motor. This accelerates the motor and insures that there will be ample vacuum or power for operating the pistons 41 and applying he brakes. The motor is thus automatically accelerated in the application cycle of the mechanism. The motor, of course, can be accelerated as usual and connecting rod I3 will then be swung moving valve II] to open position and also moving valve 9 through parts I5, I5, I'I, 2| and II.

Due to the relative areas of pistons SI and the latter will be moved to its maximum upward position as shown in Fig. 2 so that the brakes Will be applied on the trailer before the fluid acts by movement of piston l6l to set the brakes on the tractor vehicle. This is an important feature as it is very desirable to set the brakes on the trailer vehicle first. This prevents additional movement of the trailer after the tractor is retarded and thus prevents jackkniflng of the trailer or in other words, a swinging move ment of the rear end of the trailer laterally and forwardly.

To disengage the coupling means between the tractor and trailer namely members I20 and H5 the locking means (not shown) for the lever I45 is released. The valve stem I35 can then be re- I moved from its cooperating member I3I. There will be a removable connection between these parts. The lever locking means remains on the trailer unit. The tractor-carried portion of the mechanism contained in the coupling casting I I5 is disconnected from the trailer portion contained in the member I20. In this disengaging operation the compression springs I I3 and I28 move the valve member or core I3I to the limit of its disconnecting position and at this .time the radial portions of passage I36 will be in alignment with the sealing rings I28 so that there will be no leakage of brake fluid. The portion I21 moves with the member I3I. Member I3I will move until its flanged end engages the plug I34. The chambers Ill and H9 are sealed against fluid losses by the sealing cup member I31.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the parts, without departing from the scope of applicants invention, which generally stated, consists in a device capable of carrying out the objects above set forth, in the parts and combinations of parts disclosed and defined in the appended .claims.

What is claimed is:

1. A brake system for a trailer vehicle adapted to be operated from an automotive tractor vehicle, comprising, a fluid pressure cylinder. a conduit leading from said cylinder to the brake system of said trailer vehicle for conducting fluid under pressure thereto to apply the brakes to said trailer vehicle, a plunger movable in said cylinder, a control device, a plungeractuating means, means for holding said control device in position with atmospheric pressure and reduced pressure applied to said plunger actuating means to hold said plunger in brake releasing position, means for operating said control device to reverse the application of atmospheric pressure and reduced pressure to said plunger actuating means for operating said plunger actuatingmeans and moving said plunger to brake applying position to force fluid through said conduit and apply the brakes to said trailer. I

2. The structure set forth in claim 1, said plunger having a fluid containing chamber therein and having a small passage through its end disposed in said fluid pressure cylinder through which fluid may pass from said cylinder into said chamber.

3. The structure set forth in claim 1, said plunger having a chamber therein for containing fluid, said chamber communicating through a small passage with said cylinder and a vent pipe extending through the side of said plunger to adjacent the end thereof opposite said cylinder.

4. A brake system for a trailer vehicle adapted to be operated from an automotive tractor vehicle having a fluid operated brake system, 'comprising, a fluid pressure cylinder,a plunger movable therein, a conduit leading from said cylinder to the brake mechanism of said trailer for conducting fluid under pressure to said mechanism for applying the brakes, a plunger actuating device, a control device, a second control device, a connection from the intake manifold of said automotive vehicle to said control devices, means for holding said control devices in position with atmospheric pressure and reduced pressure applied to said plunger actuating means for holding said plunger in brake releasing position, means actuated by the brake applying means of said automotive vehicle for operating said second control device to reverse the application of atmospheric and reduced pressure to' said plunger actuating tons to said control device, a control plunger in device to move said plunger and force fluid to be operated from an automotive tractor vein unison, a fluid pressure cylinder at one end of said first mentioned cylinder, at plunger movable in said latter cylinder and connected to said pis-.

tons to be moved thereby, a conduit extending from said pressure cylinder to the brake system of said trailer vehicle, means for applying atmospheric pressure to one end of said power cylinder and reduced pressure to the other end thereof to .hold said plunger in brake releasing position and means operated by the brake applying means of said automotive vehicle for placing atmospheric pressure on said other end of said power cylinder and reduced pressure on said one end of said power cylinder to move said plunger to supply fluid under pressure to said first mentioned conduit and apply the brakes to said trailer vehicle.

6. The structure set forth in claim 5, said plunger being disposed in and centrally of said power cylinder.

7. A brake system for a trailer vehicle adapted to be operated from an automotive tractor 'vehicle having a fluid operated brake system, comi prising, a fluid pressure cylinder, a conduit leading from said cylinder to the brake system of said trailer vehicle for conducting fluid under pressure thereto to apply the brakes to said trailer vehicle, a plunger movable in said cylinder, an actuating means for said plunger, a control device comprising a control plunger and ports controlled thereby, connections between said ports and said actuating means for controlling said means, a second fluid pressure cylinder, a second plunger therein actuated by the operator of said trailer vehicle to apply the brakes therein, a connection between said second .pressure cylinder and said control device to move said control plunger in one direction to actuate said actuating means and first mentioned plunger, and a connection between said first mentioned cylinder and said control device to move said control plunger in the opposite direction whereby said control plunger .is held in a central position with said brakes on said trailer applied.

8. A brake system for a trailer vehicle adapted to be operated from an automotive tractor vehicle having a fluid operated brake system and a brake applying means, comprising, a power cylinder, spaced pistons therein actuated to move in unison, a fluid pressure cylinder, a plunger movable in said latter cylinder and connected to said pistons to be moved thereby, a conduit extending from said pressure cylinder to the brake system of said trailer vehicle for conducting fluid thereto to apply the brakes to said trailer vehicle, a control device, conduitsextending from the ends of said power cylinder respectively to said. control device a,- connection from the intake manifold of said automotive vehicle to said power cylinder between said pistons, a conduit extending from said power cylinder between said pissaid control device having ports for effecting and shutting off communication between said conduits, means normally holding said control plunger in position to apply atmospheric pressure to one end of said power cylinder and reduced pressure to the other end thereof through said conduits, means for actuating said control device from the brake applying means of said automotive vehicle for applying atmospheric pressure to said other end of said power cylinder and reduced pressure to said one end of said power cylinderv to move said pistons and plunger and apply fluid pressure through said first mentioned conduit to apply the brakes to said trailer vehicle.

9. A brake system for a trailer vehicle adapted to be operated from an automotive tractor vehicle having a fluid operated brake system, comprising, a fluid pressure cylinder, a conduit leading from said cylinder to the brake system of said trailer vehicle for conducting fluid under pressure thereto to apply the brakes to said trailer vehicle, a plunger movable in said cylinder, an actuating means for said plunger, a fluid pressure means actuated by the operator of said tractor vehicle for applying the brakes to said trailer vehicle, a fluid operated control device for said actuating means, a connection between said control device and said last mentioned means through which said control device is moved to operate said actuating means to operate said first mentioned plunger and apply the brakes to said trailer and a connection between said control device and flrst mentioned cylinder for moving said control device in the opposite direction until the pressure in said first mentioned connection is balanced and to stop further operation of said actuating means until more pressure is applied by the operator to said fluid pressure means.

10. A brake system for a trailer vehicle adapted to be operated from an automotive tractor vehicle having a fluid operated brake system and a brake operating means comprising a power cyllinder having spaced pistons therein connected to move in unison, a fluid pressure cylinder, a plunger secured to said pistons and movable in said fluid pressure cylinder, a conduit extending from said fluid pressure cylinder to the brake system of said second vehicle, a control device, a second conduit extending from one end of said power cylinder to said device, a third conduit extending from the other end of said power cylinder to said device, a fourth conduit extending from said power cylinder between said pistons to said device, a fifth conduit extending from said cylinder between said pistons to the intake manifold of said automotive vehicle, means for holding said device in position with atmospheric pressure applied to one end of said power cylinder through said second conduit and reduced pressure applied to the other end of said power cylinder through said third conduit and means connecting said device to said brake operating means of said automotive vehicle for moving saiddevice for applying atmospheric pressure to said other end of said power cylinder through said third conduit and reduced pressure to the opposite end of said power cylinder through said second conduit to move said plunger and force fluid through said first mentioned conduit to apply the brakes to said trailer vehicle.

11. A brake system for a trailer vehicle adapted to be operated from an automotive tractor vehicle comprising a fluid pressure cylinder, a conduit leading from said cylinder to the brake system of said trailer vehicle for conducting fluid under pressure thereto to apply the brakes to said trailer vehicle, a plunger movable in said cylinder, a control device, a plunger actuating means, a plurality of conduits leading respectively to said control device and plunger actuating means, a connection between said plunger actuating means and the intake manifold of said automotive vehicle, means for holding said control device in position with atmospheric pressure and reduced pressure applied to said plunger actuating means to hold said plunger in brake releasing position, means for actuating said control device for reversing the application of atmospheric pressure and reduced pressure to said plunger actuating means to move said plunger and apply the brakes to said trailer vehicle and an equalizing connection between said fluid pressure cylinder and said control device.

12. A brake system for a trailer vehicle adapted to be operated from an automotive tractor vehicle having a fluid operated brake system and a brake applying means, comprising, a conduit extending to the brake mechanism of said trailer vehicle for conducting fluid under pressure thereto to apply the brakes, means for forcing fluid under pressure through said conduit, means for holding said last mentioned means in brake releasing position, means actuated by the brake applying means of said automotive vehicle for operating said first mentioned means to apply the brakes on said trailer when said brakes are applied on said automotive vehicle and means for also operating said first mentioned means to apply the brakes on said trailer without operating the brakes on said automotive vehicle.

13. A brake system for a trailer vehicle adapted to be operated from an automotive tractor vehicle having a fluid operated brake system, comprising, a fluid pressure cylinder, a conduit leading from said cylinder to the brake system of said trailer vehicle for conducting fluid under pressure thereto to apply the brakes to said trailer vehicle, a plunger movable in said cylinder, a control device for said plunger, a second control device for said plunger, means actuated by the brake applying means of said automotive I vehicle to operate said second control device to cause movement of said plunger to apply the brakes on said trailer when the brakes on said automotive vehicle are applied and means for actuating said first mentioned control device to move said plunger to apply the brakes on said trailer without applying the brakes on said automotive vehicle.

14. A brake system for a trailer vehicle adapted to be operated from an automotive tractor vehicle having a fluid operated brake system and brake applying means, comprising, a fluid pressure cylinder, a conduit leading from saidcylinder to the brake system of said trailer vehicle for conducting fluid under pressure thereto to apply the brakes to said trailer vehicle, a

plunger movable in said cylinder, means actuated by the brake applying means of said automotive vehicle for forcing fluid through said conduit to apply the brakes on the trailer when the brakes are applied on said automotiveveof a vehicle comprising a conduit through which fluid is forced, a second conduit for conducting said fluid to the brake operating mechanism of said vehicle, a member having a bore therein to which said conduits are connected, a plunger movable in said bore having a passage therethrough with spaced ports leading therefrom, and means for moving said plunger into position with said passage and ports connecting said conduits so that the brakes may be operated and for moving said plunger to a position with said ports covered and preventing communication between said conduits so that no fluid can be forced through said second conduit.

6. A control device for a brake mechanism having in combination, a casing having a bore therein, a conduit connected to said casing and communicating with said bore adapted to supply fluid under pressure thereto, a second conduit communicating with said bore and extending to the brake operated mechanism of said vehicle, said bore having enlarged'portions with which said conduits respectively communicate, said said bore whereby fluid can pass from said first mentioned conduit to said second conduit and for moving said plunger to a position with said outlets closed by the walls of said bore so that communication between said conduits is prevented.

17. A brake system for a trailer vehicle adapted to be operated from an automotive vehicle having a fluid operated brake system and a brake applying means including a fluid cylinder and piston therein, said piston being moved by the operator, comprising, a conduit extending to the brake mechanism of said trailer vehicle for conducting fluid under pressure thereto to apply the brakes, a cylinder for containing fluid with which said conduit connects, a plunger in said cylinder for forcing fluid through said conduit, a control device for said plunger including a cylinder and a plunger therein, said cylinder having a plurality of ports controlled by parts of said plunger, a connection between said brake applying cylinder and said cylinder of said control device for actuating the plunger of said control device and a connection between said first mentioned cylinder and the cylinder of said control device for effecting a balance or equalization of the fluid in said cylinder for holding said plunger in certain positions.

18. A brake system for a trailer vehicle adapted to be operated from an automotive tractor vehicle having a fluid operated brake system and an internal combustion motor comprising, a fluid pressure cylinder, a plunger movable therein, a conduit leading from said cylinder to the brake mechanism of said trailer for conducting fluid under pressure to said mechanism for applying ture and said control device.

, ROY ooawm HOYI'. 

